The current state of knowledge of allergic reactions to fungi is best described as confusing and complex, although fungal spores are probably one of the most abundant sources of inhaled organic material in the environment. During the last three years, we have studied allergic reactions of individuals with symptoms of respiratory allergy to spores from Basidiomycetes (a major class of fungi). Our studies indicate that extracts of basidiospores can be prepared that elicit a significant number of specific skin test and RAST reactions in subjects with histories of respiratory allergies, particularly those with asthma. Several basidiospore extracts have skin test reactivity the exceeded those obtained common fungi and were similar to the prevalence of skin reactions to some tree pollens. Preliminary investigations have begun to isolate and characterize important basidiospore allergens. Fractionation of basidiospore extracts by gel filtration on Sephadex G-75 have resulted in considerable purification of spore allergens. RAST inhibition studies have demonstrated significant cross-allergenicity of several basidiospore species. Based on the fact that we have obtained sufficient quantities of pure spores, extracted active allergens from these spores, and demonstrated a number of individuals with positive skin and RAST reactivity to these spores, our grant renewal application addresses the following objectives: (1) Continue identification, isolation, and characterization of clinically important basidiospore allergens of five basidiomycete species (2) measure the prevalence of skin test and IgE antibody reactivity to basidiospores throughout the United States, since the preliminary evidence in Seattle and New Orleans suggest that they are important aeroallergens; (3) assess bronchial reactivity to basidiospore allergens by provocative inhalation challenge. Although the task of fungal allergen characterization is much more difficult than with pollens, the need for standardized fungal extracts is essential. The increased number of fungal samples which are commercially available and are being used in the practice of allergy for skin testing and immunotherapy emphasizes the need to identify and characterize further fungal allergens. By identification and purification of basidiospore allergens, determination of prevalence of skin and RAST reactivity, and analysis of patterns of basidiospore allergen induced bronchial reactivity, our studies will help further understanding of mold asthma.